Forging-mediated microstructural control and enhanced properties in lightweight refractory high-entropy alloys Al20Nb15Ti35Zr30

With the booming development of modern industry, particularly the aviation and aerospace industries, the exploration of materials with more superior properties has attracted extensive attention over the past few decades. Refractory high-entropy alloys (RHEAs) have garnered significant interest due to their series of excellent properties at both room and elevated temperatures, such as high strength, high ductility, corrosion resistance, and outstanding radiation resistance. The NbTiZr medium-entropy alloy (MEA) has been extensively studied by numerous scholars and researchers. In addition to its remarkable yield strength, its good compressive plasticity endows it with the potential to become a more advanced material.

Building on this, the present study designed a lightweight refractory high-entropy alloy Al₂₀Nb₁₅Ti₃₅Zr₃₀, and on this basis, a small amount of Cr element was incorporated to form a multiphase alloy with the BCC phase as the matrix and Laves and Al?Zr? phases as secondary phases. The microstructure and properties of the alloy were regulated through multi-directional forging and heat treatment. Through a reasonable thermal processing technique, the room-temperature compressive strength of the alloy reached 1870.1 MPa, with a specific yield strength of 338.2 N·m/Kg.

This paper investigates the microstructure evolution mechanism of the alloy under different forging temperatures and its influence on properties, covering the evolution path of precipitated phases during thermal deformation, the room-temperature strengthening mechanism, the alloy failure mechanism during high-temperature compression, the formation of multi-scale heterogeneous microstructure, and its strengthening and toughening mechanism. Our research provides a certain theoretical basis for the evolution of precipitated phases and microstructure control in lightweight refractory high-entropy alloys, and offers new insights for the further development of their thermal processing techniques.

Zhang Wei is a Ph.D. candidate at the School of Mechanical Engineering, Taiyuan University of Technology. His research is focused on the development of hot working processes for high-entropy alloys and the regulation of microstructure and properties, under the supervision of Professor Han Jianchao.